JP6884561B2 - Electric work machine - Google Patents

Description

The present disclosure relates to a technique for controlling a rotating motor in an electric working machine having a motor.

Various electric work machines configured to drive a motor via a drive circuit having a plurality of switching elements may be equipped with a function for protecting the motor from overcurrent. Patent Document 1 describes a technique for stopping a motor by turning off all switching elements constituting the inverter when an overcurrent is detected in an electric tool having an inverter as a drive circuit.

Japanese Unexamined Patent Publication No. 2013-81285

However, if all the switching elements of the drive circuit are turned off while the motor is energized, a regenerative current that flows from the motor to the power supply is generated mainly due to the magnetic energy stored in the motor, and this regenerative current raises the power supply voltage. I have something to do. When the power supply voltage rises due to the regenerative current, various other circuits and elements that operate by receiving power from the power supply may be adversely affected.

One aspect of the present disclosure is that in an electric working machine configured to drive a motor via a drive circuit having a plurality of switching elements, a regenerative current from the motor to the power supply is generated when the energization from the power supply to the motor is stopped. The purpose is to suppress the flow.

The electric work machine in one aspect of the present disclosure includes a motor, a drive circuit, and a control unit. The motor has a plurality of terminals for inputting power from a DC power source. The drive circuit includes a plurality of positive electrode side energization paths connecting each of the plurality of terminals of the motor and the positive electrode side of the DC power supply, and a plurality of terminals connecting each of the plurality of terminals of the motor and the negative electrode side of the DC power supply. It has a plurality of switching elements individually provided in the negative electrode side energization path to conduct and cut off each energization path. The drive circuit further includes a plurality of rectifying elements individually connected in parallel to each of the plurality of switching elements so as to allow energization from the negative electrode side to the positive electrode side of the DC power supply. The control unit is configured to control the drive of the motor by individually controlling the on and off of a plurality of switching elements included in the drive circuit.

Then, the control unit is configured to execute the normal drive control and the stop specific control. The normal drive control is performed on one of the positive electrode side switching elements, which are the switching elements provided in each positive electrode side energization path among the plurality of switching elements, and on the negative electrode side of the plurality of switching elements. This is a process of rotating the motor by turning on any one of the negative electrode side switching elements provided in the energization path. The stop specific control is performed for a predetermined period for the two switching elements that are turned on when the stop condition for stopping the power supply from the DC power supply to the motor is satisfied during the rotation of the motor by the normal drive control. This is a process in which one is turned off and the other is kept in the on state.

The DC power supply referred to here means all power sources that supply DC power to the drive circuit, and the power input to the electric work machine from the outside of the electric work machine is limited to the power from the DC power supply. It's not something. That is, any form of power source configured to supply DC power to the drive circuit is included in the DC power supply here.

Further, the terminal referred to here is a concept including all elements for power input, which are electrically connected to the internal winding in order to supply electric power from the DC power supply to the internal winding.
In an electric work machine having such a configuration, when a stop condition is satisfied during normal drive control, one of the two switching elements to be turned on is not turned off, but one is turned off and the other is turned on. It is maintained in a state.

When one of the two switching elements that are turned on is turned off, the energization from the DC power supply to the motor is stopped, and the recirculation current flows due to the magnetic energy stored in the motor. This regenerative current is not a regenerative current that regenerates electric power from the motor to the DC power supply, but a current that flows through a loop-shaped energization path formed between the drive circuit and the motor. Here, a rectifying element connected in parallel to another switching element connected to the terminal of the same motor as the switching element turned off by the transition to the specific control at the time of stop is referred to as a reverse side rectifying element. .. The recirculation current is the current that flows through the motor, the reverse side rectifying element, and one switching that is held on.

As described above, according to the electric working machine of the present disclosure, when the stop condition is satisfied during the normal drive control, the energization from the DC power supply to the motor is stopped, and the energization path of the recirculation current is formed for a predetermined period. The magnetic energy of the motor is consumed by the recirculation current flowing through this energization path. Therefore, the regenerative current from the motor to the DC power supply can be suppressed when the energization from the DC power supply to the motor is stopped.

The predetermined period may be appropriately determined, but may be set as follows, for example. That is, the predetermined period may be set to a predetermined period after the start of the specific control at the time of stop and the time required for the recirculation current to become zero or more has elapsed.

According to such a configuration, all the magnetic energy stored in the motor when the stop condition is satisfied can be consumed by the recirculation current, so that the regenerative current from the motor to the DC power supply can be suppressed more effectively.

The control unit is configured to perform PWM control as normal drive control, in which one of the positive electrode side switching element and the negative electrode side switching element to be turned on is fixed in the on state and the other switching element is PWM-driven. You may be. Then, in the stop-time specific control, the switching element that was PWM-driven when the stop condition is satisfied is turned off, and the switching element that is fixed to the on state when the stop condition is satisfied is kept in the on state. It may be.

According to such a configuration, when the stop condition is satisfied, the control state of the switching element fixed to the ON state may be continued as it is, and it is not necessary to change the state of the switching element. Therefore, it is possible to reduce the processing load required for switching from the normal drive control to the stop specific control when the stop condition is satisfied.

The electric work machine may include a drive state detection unit that detects the drive state of the motor. In that case, the control unit may be configured to perform an abnormality determination process for determining whether or not the drive state of the motor is an abnormal state based on the detection result by the drive state detection unit. The stop condition may be that the drive state of the motor is determined to be an abnormal state by the abnormality determination process.

According to such a configuration, when an abnormal state occurs, it is possible to stop the energization from the DC power supply to the motor while suppressing the generation of the regenerative current from the motor to the DC power supply. Depending on the content of the abnormal state, it is assumed that an excessive current will flow through the motor. In such a case, if all the switching elements are turned off, an excessive regenerative current may flow from the motor to the DC power supply. On the other hand, when an abnormal state occurs, specific control is performed when the motor is stopped, and the magnetic energy of the motor is consumed by the recirculation current. Therefore, even if an excessive current flows through the motor when an abnormal state occurs, the motor is regenerated to a DC power supply. The current can be effectively suppressed.

The electric work machine may include an operation unit operated to instruct the rotation or stop of the motor. The stop condition may be that an operation for stopping the rotation of the motor is performed on the operation unit.

According to such a configuration, when an operation for stopping the rotation of the motor is performed on the operation unit, the rotation in the current rotation direction is stopped while suppressing the regenerative current from the motor to the DC power supply. Can be made to.

The electric work machine may include a current detection unit. The current detection unit is configured to detect the value of the current flowing from the DC power supply to the motor via the drive circuit. Then, when the value of the current detected by the current detection unit is equal to or greater than the threshold value after the start of the specific control at the time of stop, the control unit may turn off the switching element held in the ON state.

When the specific control at the time of stop is started, only one of the plurality of switching elements is turned on, so that the energization from the DC power supply to the motor should be stopped. Nevertheless, if the value of the current detected by the current detection unit is equal to or higher than the threshold value even after the start of the specific control at the time of stop, that is, the current having a value equal to or higher than the threshold value is energized from the DC power supply, some abnormality occurs. There may be. Therefore, if a current with a value equal to or higher than the threshold value is detected by the current detector even after the start of the specific control at the time of stop, the switching element held in the ON state is turned off to suppress the energized current. can do.

It is a side view of the whole electric work machine of embodiment. It is a block diagram which shows the electric structure of the electric work machine of 1st Embodiment. It is explanatory drawing which shows an example of each current path at the time of the normal drive control, and when all the switching elements are turned off during the normal drive control in the electric work machine of 1st Embodiment. It is explanatory drawing which shows the operation example in the case of turning off all the switching elements during the normal drive control in the electric work machine of 1st Embodiment. It is explanatory drawing which shows an example of each current path in the electric working machine of 1st Embodiment, at the time of the normal drive control, and at the time of shifting from the normal drive control to the stop specific control. It is explanatory drawing which shows the operation example in the case of shifting to the specific control at the time of stop during the normal drive control in the electric work machine of 1st Embodiment. It is a flowchart which shows the energization stop process of embodiment. It is explanatory drawing which shows an example of each current path in the electric working machine of 2nd Embodiment, at the time of the normal drive control, and at the time of shifting from the normal drive control to the stop specific control. It is explanatory drawing which shows the operation example at the time of shifting to the specific control at a stop during the normal drive control in the electric work machine of 3rd Embodiment. It is a block diagram which shows the electric structure of the electric work machine of 4th Embodiment. It is explanatory drawing which shows an example of each current path at the time of the normal drive control, and when all the switching elements are turned off during the normal drive control in the electric work machine of 4th Embodiment. It is explanatory drawing which shows the operation example at the time of turning off all the switching elements during the normal drive control in the electric work machine of 4th Embodiment. It is explanatory drawing which shows an example of each current path at the time of a normal drive control, and at the time of shifting from the normal drive control to the stop specific control in the electric work machine of 4th Embodiment. It is explanatory drawing which shows the operation example in the case of shifting to the specific control at the time of stop during the normal drive control in the electric work machine of 4th Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. First Embodiment]
(1-1) Overall Configuration of Electric Work Machine As shown in FIG. 1, the electric work machine 1 of the present embodiment is configured as a so-called driver drill mainly used for drilling holes or tightening screws in a member to be machined. Has been done. The electric work machine 1 includes a main body 3 and a battery pack 5.

The battery pack 5 houses the battery 15. The battery pack 5 is removable from the main body 3, and is configured to be able to supply electric power from the battery 15 to the main body 3 when mounted on the main body 3.

The main body 3 includes a motor housing 6, a gear housing 7, a drill chuck 8, and a hand grip 9. The motor housing 6 houses the motor 20. The motor 20 generates a driving force for rotationally driving the drill chuck 8.

The gear housing 7 is arranged in front of the motor housing 6. The gear housing 7 houses a gear mechanism (not shown) that transmits the driving force of the motor 20 to the drill chuck 8. The drill chuck 8 is arranged in front of the gear housing 7. The front end of the drill chuck 8 is provided with a mounting mechanism for attaching and detaching a tool bit.

The hand grip 9 is arranged below the motor housing 6. The hand grip 9 is formed so that the user of the electric work machine 1 can grip the hand grip 9 with one hand. A trigger switch 10 is provided in front of the upper part of the hand grip 9. The trigger switch 10 is operated by the user of the electric work machine 1 to drive or stop the motor 20.

When the trigger switch 10 is pulled, the motor 20 rotates, and when the trigger switch 10 is not pulled, the motor 20 stops. Further, when the trigger switch 10 is pulled, the rotation speed of the motor 20 changes according to the amount of the pulling operation (hereinafter referred to as the pulling amount). That is, the larger the pulling amount, the higher the rotation speed of the motor 20. The rotation speed of the motor 20 may be a constant speed regardless of the pulling amount of the trigger switch 10.

A forward / reverse switch 12 is provided on the lower side of the motor housing 6. The forward / reverse switch 12 is a switch operated by the user to selectively switch the rotation direction of the motor 20 to either forward rotation or reverse rotation. Regarding the rotation direction of the motor 20, which direction is defined as normal rotation and which direction is defined as reverse rotation may be appropriately determined.

A mode changeover switch 14 is provided on the upper surface of the motor housing 6. The mode changeover switch 14 is a switch operated by the user to selectively switch the speed mode of the motor 20 to any of a plurality of types of modes. In the present embodiment, the speed mode has, for example, a low speed mode and a high speed mode, and one of the speed modes is set by the mode changeover switch 14. When the trigger switch 10 is pulled, the rotation speed is higher in the high speed mode than in the low speed mode for the same pull amount.

A battery pack mounting portion 16 for detachably mounting the battery pack 5 is provided at the lower end of the hand grip 9. The battery pack mounting portion 16 is configured so that the battery pack 5 can be attached to and detached from the battery pack mounting portion 16 by sliding the battery pack 5 in the front-rear direction.

(1-2) Electrical Configuration of Electric Working Machine Next, the electrical configuration of the electric working machine 1 will be described with reference to FIG. FIG. 2 shows a state in which the battery pack 5 is attached to the main body 3. As shown in FIG. 2, the electric work machine 1 includes a battery pack 5, a motor 20, a drive circuit 21, a control unit 22, and a rotation position detection unit 23. When the battery pack 5 is mounted on the main body 3, the electric power of the battery 15 in the battery pack 5 (hereinafter, battery power) is input to the drive circuit 21 and the control unit 22. The control unit 22 operates by the battery power when the battery power is input.

The motor 20 is driven by the battery power supplied from the battery 15 via the drive circuit 21. The motor 20 of this embodiment is a brushless motor. The battery power supplied from the battery 15 is converted into three-phase power by the drive circuit 21 and supplied to the motor 20.

The motor 20 has three windings 31, 32, 33. In the present embodiment, these three windings 31, 32, and 33 are delta-connected, but this is just an example, and may be connected by a connection method other than delta connection. Further, the motor 20 includes three terminals 20a, 20b, and 20c as terminals for power input.

The specific shape, structure, and the like of the terminals 20a, 20b, and 20c are not particularly limited, and any form capable of supplying battery power to the windings 31, 32, and 33 can be adopted. For example, it may be a conductor terminal having a specific shape having a hole for inserting an electric wire, a lead wire drawn from the main body of the motor 20, or a printed circuit board electrically connected to the motor 20. , Specific parts or parts electrically connected to the windings 31, 32, 33 and the like.

The rotation position detection unit 23 is configured to output a signal corresponding to the rotation position of the motor 20, specifically, a signal corresponding to the rotation position of the rotor of the motor 20. The rotation position detection unit 23 has three Hall sensors. Each Hall sensor is arranged around the rotor of the motor 20 at intervals of an electric angle of 120 degrees. The signals output from the three Hall sensors are input to the control unit 22. The control unit 22 detects the rotation position and rotation speed of the motor 20 based on the signals input from the rotation position detection unit 23, that is, each signal from the three Hall sensors.

In the present embodiment, the drive circuit 21 is configured as a so-called three-phase full bridge circuit having six switching elements Q1, Q2, Q3, Q4, Q5, and Q6.
In the drive circuit 21, the three switching elements Q1, Q2, and Q3 as high-side switches are energized on each positive electrode side, which is an energizing path connecting the terminals 20a, 20b, 20c of the motor 20 and the positive electrode side of the battery 15. Each route is provided. Further, the three switching elements Q4, Q5, and Q6 as low-side switches are connected to the negative electrode side energization paths, which are the energization paths connecting the terminals 20a, 20b, 20c of the motor 20 and the negative electrode side of the battery 15, respectively. It is provided. Each of the switching elements Q1 to Q6 conducts the corresponding energization path when it is turned on, and shuts off the corresponding energization path when it is turned off.

That is, of the three terminals 20a, 20b, and 20c of the motor 20, the terminal 20a has a switching element Q1 as a high-side switch (hereinafter, also referred to as "U-phase high-side switch Q1") and a switching element as a low-side switch. Q4 (hereinafter, also referred to as "U-phase low side switch Q4") is connected. Further, the terminal 20b has a switching element Q2 as a high-side switch (hereinafter, also referred to as "V-phase high-side switch Q2") and a switching element Q5 as a low-side switch (hereinafter, also referred to as "V-phase low-side switch Q5"). Is connected. Further, the terminal 20c has a switching element Q3 as a high-side switch (hereinafter, also referred to as "W-phase high-side switch Q3") and a switching element Q6 as a low-side switch (hereinafter, also referred to as "W-phase low-side switch Q6"). Is connected.

Each switching element Q1 to Q6 is an n-channel MOSFET in this embodiment. Therefore, diodes (so-called parasitic diodes) D1 to D6 in the forward direction from the source to the drain are connected in parallel between the drain and the source of the switching elements Q1 to Q6, respectively. The diodes D1 to D6 are connected so as to allow energization from the negative electrode side to the positive electrode side of the battery 15.

The control unit 22 has a one-chip microcomputer including a CPU 22a, a memory 22b, and the like. The memory 22b includes various semiconductor memories such as RAM, ROM, and non-volatile memory. Various programs and data for realizing various functions of the control unit 22 are stored in the memory 22b. Various functions possessed by the control unit 22 are realized by the CPU 22a executing various programs stored in the memory 22b. The program stored in the memory 22b includes a program for energization stop processing shown in FIG. 7, which will be described later.

The various functions realized by the control unit 22 are not limited to software processing, and some or all of the functions may be realized by using hardware in which a logic circuit, an analog circuit, or the like is combined. Further, the configuration in which the control unit 22 has a one-chip microcomputer is merely an example, and the control unit 22 may adopt various other configurations capable of realizing the function as the control unit 22.

A trigger switch 10, a forward / reverse switch 12, a mode changeover switch 14, and an acceleration sensor 26 are connected to the control unit 22. From the trigger switch 10, the forward / reverse switch 12, and the mode changeover switch 14, signals indicating the operating state of the switch are input to the control unit 22, respectively.

The control unit 22 determines whether or not the trigger switch 10 is being pulled and the amount of operation when the trigger switch 10 is being pulled, based on the signal input from the trigger switch 10, and controls according to the determination result. I do.

The control unit 22 stops all the drive signals to the switching elements Q1 to Q6 in the drive circuit 21 while the trigger switch 10 is off, that is, while the trigger switch 10 is not pulled. All the switching elements Q1 to Q6 are turned off to stop the motor 20.

On the other hand, when the trigger switch 10 is on, that is, when the trigger switch 10 is pulled, the control unit 22 rotates the motor 20 by performing normal drive control. The control unit 22 detects the rotation position of the motor 20 based on the signal input from the rotation position detection unit 23 during the execution of the normal drive control, and each switching element Q1 of the drive circuit 21 according to the detected rotation position. By individually turning on and off of Q6, the energization from the battery 15 to the motor 20 is controlled to rotate the motor 20.

In the normal drive control of the present embodiment, a drive signal is output to any one of the three high-side switches Q1 to Q3 and one of the three low-side switches Q4 to Q6, and these two switching elements are used. By turning on, the motor 20 is energized to rotate the motor 20. The control unit 22 rotates the motor 20 by switching one switching element to be turned on on the high side side and one switching element to be turned on on the low side side according to the rotation position of the motor 20.

In the normal drive control, the two switching elements to be turned on may be fixed to the on state together, but in the present embodiment, the PWM control is adopted as the normal drive control. That is, in the normal drive control of the present embodiment, PWM control is performed in which one of the two switching elements to be turned on is fixed in the ON state and the other switching element is PWM-driven. The PWM drive is a well-known drive method in which ON and OFF are periodically alternately repeated at a set duty ratio.

Further, in the normal drive control, the control unit 22 determines the operating state of the forward / reverse switch 12 based on the signal from the forward / reverse switch 12. Then, the rotation direction of the motor 20 is set to either forward rotation or reverse rotation according to the operation state, and the drive circuit 21 is controlled so that the motor 20 rotates in the set rotation direction.

Further, in the normal drive control, the control unit 22 determines the operation state of the mode changeover switch 14 based on the signal input from the mode changeover switch 14, and sets the operation mode to the low speed mode and the high speed according to the operation state. Set to one of the modes. Then, the drive circuit 21 is controlled so that the motor 20 rotates at a rotation speed corresponding to the set operation mode.

The acceleration sensor 26 detects the acceleration generated in the electric work machine 1 and outputs a signal indicating the detected acceleration to the control unit 22. As an example, the acceleration sensor 26 of the present embodiment is a three-axis acceleration sensor configured to be able to independently detect accelerations of three axes (X-axis, Y-axis, and Z-axis) orthogonal to each other.

When a worker is working with the electric work machine 1, a specific behavior occurs in the electric work machine 1 due to various factors such as a state of a work target and a state of use of the electric work machine 1 by the worker. there's a possibility that. Specifically, as a specific behavior, for example, an impact is applied to the electric work machine 1 from the outside due to a drop or a collision, or the electric work machine 1 in operation receives a reaction from a work target, so that the entire electric work machine 1 is swung around. In addition, when the operating electric work machine 1 receives a reaction from the work target, a so-called kickback occurs in which the electric work machine 1 moves away from the work target.

All of these illustrated specific behaviors are behaviors in which a large acceleration is likely to be generated in the electric working machine 1 when the specific behavior occurs. Therefore, the control unit 22 detects the acceleration generated in the electric work machine 1 based on the signal input from the acceleration sensor 26 while the motor 20 is being driven, and the electric work machine 1 generates a specific behavior based on the acceleration. Determine if you did. Then, when it is determined that the specific behavior has occurred, the energization from the battery 15 to the motor 20 is stopped by performing the specific control at the time of stopping, which will be described later.

It should be noted that it may be appropriately determined how to specifically determine whether or not a specific behavior has occurred based on the detected acceleration. For example, it may be determined that a specific behavior has occurred when any one of the accelerations of the three axes exceeds the threshold value.

Further, a current detection unit 24 for detecting the value of the current (hereinafter, power supply current) supplied from the battery 15 to the motor 20 is provided in the energization path from the battery 15 to the motor 20. The current detection unit 24 has, for example, a shunt resistor provided on the energization path from the battery 15 to the motor 20, and the voltage across the shunt resistor is sent to the control unit 22 as a detection signal indicating the value of the power supply current. Output. The current detection unit 24 has a shunt resistance as an example, and may have another configuration capable of outputting a detection signal according to the value of the power supply current.

The control unit 22 detects the value of the power supply current based on the detection signal input from the current detection unit 24. Then, various controls are performed according to the detected value.
(1-3) Specific control when stopped The control unit 22 starts normal drive control when the trigger switch 10 is turned on, and then when the stop condition for stopping the power supply from the battery 15 to the motor 20 is satisfied. , Performs specific control when stopped. Then, after executing the specific control at the time of stopping, finally, the motor 20 is maintained in the stopped state by turning off all the switching elements Q1 to Q6 of the drive circuit 21.

Here, as a specific method for stopping the rotation of the motor 20 during normal drive control, for example, it is conceivable to turn off all the switching elements Q1 to Q6 of the drive circuit 21. However, when the normal drive control is performed, that is, the switching elements are turned on one by one on the high side side and one on the low side side, and the two switching elements turned on are turned off together, the motor 20 is turned on. A regenerative current is generated from the battery 15 side, and the influence of this regenerative current may affect the control unit 22.

A more specific description will be given with reference to FIGS. 3 and 4. FIG. 3 is an excerpt of the circuit configuration and the control unit 22 from the battery 15 to the motor 20 via the drive circuit 21 from the electrical configuration of the entire electric work machine 1 shown in FIG. The same applies to FIGS. 5 and 8 described later.

In the normal drive control, for example, as shown in FIG. 3, it is assumed that the U-phase high-side switch Q1 and the W-phase low-side switch Q6 are turned on. In this case, a current flows from the battery 15 to the motor 20 along the path shown by the broken line arrow in FIG. That is, a current flows from the positive electrode of the battery 15 through the U-phase high-side switch Q1, the motor 20, the W-phase low-side switch Q6, and the current detection unit 24 to the negative electrode of the battery 15.

Of the six switching elements Q1 to Q6, the two switching elements that are turned on are sequentially switched as shown in FIG. 4 according to the rotation position of the motor 20. As described above, in the normal drive control, one of the two switching elements to be turned on is fixed in the ON state and the other switching element is PWM-driven. , It is omitted that the PWM drive is specified. However, in FIG. 9, which will be described later, the PWM-driven switching element is clearly shown.

Further, in FIG. 4, the “power supply voltage” is the voltage of the energization path from the positive electrode of the battery 15 to the drive circuit 21 and the control unit 22, that is, the energization path to which the voltage of the battery 15 is applied. The "motor current" is a general term for U-phase current, V-phase current, and W-phase current input from the drive circuit 21 to the terminals 20a, 20b, and 20c of the motor 20. The U-phase current is the current input to the first terminal 20a, the V-phase current is the current input to the second terminal 20b, and the W-phase current is the current input to the third terminal 20c. Further, in FIG. 4, the period before the time t2 is the period during which the normal drive control is executed, and the time t2 is the timing at which the normal drive control is switched to the stop specific control.

The stop condition for switching from the normal drive control to the specific control at the time of stop may be appropriately determined. In the present embodiment, the stop conditions are set such that the trigger switch 10 is turned off, the value of the power supply current exceeds the first overcurrent threshold value, and a specific behavior occurs.

Of these stop conditions, the control unit 22 determines whether or not the trigger switch 10 is turned off based on the signal input from the trigger switch 10 to the control unit 22. Further, whether or not the value of the power supply current exceeds the first overcurrent threshold value is determined based on the detection signal input from the current detection unit 24. Further, as described above, whether or not the specific behavior has occurred is determined based on the signal input from the acceleration sensor 26.

Whether or not a specific behavior has occurred may be determined based on other physical quantities, not limited to the signal from the acceleration sensor 26. For example, when a specific behavior occurs, the rotation speed of the motor 20 may change abruptly. Therefore, a threshold value may be set for the absolute value of the change rate of the rotation speed, and when the absolute value of the change rate of the rotation speed exceeds the threshold value, it may be determined that a specific behavior has occurred. Further, when a specific behavior occurs and the rotation speed of the motor 20 changes abruptly, the value of the power supply current may also change abruptly accordingly. Therefore, a threshold value may be set for the absolute value of the rate of change of the power supply current, and when the absolute value of the rate of change of the power supply current exceeds the threshold value, it may be determined that a specific behavior has occurred.

As shown in FIG. 4, during the period in which the normal drive control is performed before the time t2, the switching elements to be turned on are sequentially switched according to the rotation position of the motor 20. Then, each time the switching element to be turned on is switched, the motor current also changes.

Then, it is assumed that an abnormal state in which the motor 20 locks occurs at time t1. That is, at time t1, it is assumed that the rotation of the motor 20 is forcibly decelerated or stopped due to an external factor. At time t1, as shown in FIG. 4, the U-phase high-side switch Q1 and the W-phase low-side switch Q6 are turned on, that is, the current is flowing along the path indicated by the broken line arrow in FIG. is there.

When the motor 20 is locked at time t1 and the rotation speed is decelerated or stopped, the value of the power supply current increases as compared with the normal driving. That is, in the motor current, the current values of both the U-phase current and the W-phase current increase in the respective energizing directions.

Then, when the value of the power supply current exceeds the first overcurrent threshold value at time t2, when both the two switching elements Q1 and Q6 that are turned on are turned off, the magnetic energy stored in the motor 20 causes the battery. A regenerative current to 15 is generated.

The regenerative current in this case is generated as shown by the waveforms of the power supply current and the motor current shown between the time t2 and the time t3 in FIG. 4, and in the path indicated by the single-point chain arrow in FIG. Then, as shown in FIG. 4, the power supply voltage temporarily rises due to this regenerative current. When the power supply voltage rises, it means that the voltage of the positive electrode side energization path connected to the positive electrode of the battery 15 rises. Therefore, when the power supply voltage rises, a voltage higher than the battery voltage is applied to each part including the control unit 22 which is configured to input the battery voltage, and these parts fail or malfunction. There is a possibility of doing so.

Therefore, when the stop condition is satisfied during the normal drive control, the control unit 22 of the present embodiment executes the stop specific control for a predetermined period. The stop specific control is a control in which only one of the two switching elements that are turned on when the stop condition is satisfied is turned off and the other is kept in the on state.

An example of the stop specific control will be specifically described with reference to FIGS. 5 and 6. In the present embodiment, when the stop condition is satisfied during the normal drive control, the switching element on the high side side of the two ON switching elements is turned off as the stop specific control, and the switching element on the low side side is turned off. Keeps it on. In FIG. 5, the current path during normal drive control indicated by the broken line arrow is the same as that in FIG. Further, in FIG. 6, the operation example before the time t2 is exactly the same as the operation example before the time t2 in FIG.

As shown in FIG. 6, when the motor 20 is locked at time t1 and the power supply current value rises, and when the power supply current value exceeds the first overcurrent threshold value at time t2, the stop specific control is performed. Will be done. In the present embodiment, the predetermined period during which the stop-time specific control is executed is a period from the timing when the value of the power supply current exceeds the first overcurrent threshold value to the timing when the predetermined specific execution time elapses. In FIG. 6, the time t2 is the start of the predetermined period, and the time t5 when the specific execution time elapses from the time t2 is the end of the predetermined period.

In the example of FIG. 6, the U-phase high-side switch Q1 and the W-phase low-side switch Q6 are turned on at the time t2 when the value of the power supply current exceeds the first overcurrent threshold value. That is, the current flows along the path indicated by the broken line arrow in FIG. When the stop specific control is executed in this state, the U-phase high-side switch Q1 is turned off and the W-phase low-side switch Q6 is held in the on state, as shown in FIG.

As a result, a circulating current flows between the motor 20 and the drive circuit 21 along the path shown by the alternate long and short dash arrow in FIG. That is, a recirculation current flows from the third terminal 20c of the motor 20 through the diode D4 of the W-phase low-side switch Q6 and the U-phase low-side switch Q4 to the first terminal 20a of the motor 20. The recirculation current is not a current that regenerates the magnetic energy of the motor 20 into the battery 15, but is a loop-shaped current that flows between the motor 20 and the drive circuit 21. The magnetic energy of the motor 20 is consumed by this recirculation current.

Therefore, when the stop specific control is started at time t2, the power supply current detected by the current detection unit 24 becomes 0 as shown in FIG. Then, a recirculation current is formed by the U-phase current and the W-phase current. This recirculation current gradually decreases and becomes 0 at time t4. Then, at time t5, the stop specific control ends. After the end of the stop specific control, in the present embodiment, all the switching elements Q1 to Q6 of the drive circuit 21 are turned off.

The specific execution time, which is the length of the predetermined period during which the stop-time specific control is executed, that is, the time from time t2 to time t5 in FIG. 6, is the time required for the recirculation current to become zero in the present embodiment. It is set as above. The time from the start of the stop specific control at time t2 until the recirculation current becomes zero varies depending on the value of the power supply current at the start of the stop specific control and various other factors. Moreover, since the recirculation current does not flow through the current detection unit 24, the value of the recirculation current cannot be detected by the current detection unit 24.

Therefore, in the present embodiment, when the stop specific control is started in the state where the current of the first overcurrent threshold is flowing based on the electrical characteristics of the entire path through which the recirculation current flows, the first overcurrent threshold, and the like. The time required for the recirculation current to become zero is theoretically or experimentally obtained, and a value obtained by adding a certain margin to the obtained time is set as the specific execution time.

(1-4) Energization stop processing Next, the energization stop processing executed in order to realize the transition from the normal drive control to the stop specific control will be described with reference to FIG. 7. When the normal drive control is started by turning on the trigger switch 10, the control unit 22 executes the energization stop process of FIG. 7 in parallel with the energization drive control. Specifically, the CPU 22a executes the stop specific control by the control unit 22.

When the energization stop process of FIG. 7 is started, the control unit 22 determines in S110 whether or not the value of the power supply current is larger than the first overcurrent threshold value. When the value of the power supply current is larger than the first overcurrent threshold value, that is, when the stop condition is satisfied, the normal drive control is switched to the stop specific control in S140. That is, of the two switching elements that are currently turned on, the switching element on the high side side is turned off, and the switching element on the low side side is kept in the on state.

In S110, when the value of the power supply current is equal to or less than the first overcurrent threshold value, the process proceeds to S120. In S120, it is determined whether or not a specific behavior has occurred. When the specific behavior occurs, that is, when the stop condition is satisfied, the normal drive control is switched to the stop specific control in S140. If no specific behavior has occurred, the process proceeds to S130.

In S130, it is determined whether or not the trigger switch 10 is turned off. When the trigger switch 10 is turned off, that is, when the stop condition is satisfied, the normal drive control is switched to the stop specific control in S140. If the trigger switch 10 is turned on, the process returns to S110. The fact that the negative determination is made in S130 and the return to S110 means that the stop condition is not satisfied, and in that case, the normal drive control is continued.

After switching from the normal drive control to the stop specific control in S140, in S150, it is determined whether or not the value of the power supply current exceeds the second overcurrent threshold value. In the stop-time specific control, one of the six switching elements Q1 to Q6 of the drive circuit 21 is turned on, so the value of the power supply current should be zero. Nevertheless, if the value of the power supply current exceeds the second overcurrent threshold value, there is a possibility that some abnormality has occurred, for example, one of the switching elements has a short-circuit failure.

Therefore, when the value of the power supply current exceeds the second overcurrent threshold value in S150, all the switching elements Q1 to Q6 of the drive circuit 21 are turned off in S170 to end the energization stop process. If the value of the power supply current is equal to or less than the second overcurrent threshold value in S150, the process proceeds to S160. The first overcurrent threshold value and the second overcurrent threshold value may be appropriately determined. Further, the magnitude relationship between these two overcurrent threshold values may be appropriately determined, and both may be set to the same value.

In S160, it is determined whether or not the specific execution time has elapsed after switching to the stop-time specific control in S140. If the specific execution time has not elapsed, the process returns to S150. If the specific execution time has elapsed, the process proceeds to S170.

(1-5) Effects of First Embodiment According to the first embodiment described above, the following effects are obtained.
That is, when the stop condition is satisfied during the normal drive control, the control unit 22 turns off the high-side switch among the two switching elements that are turned on at that time, and keeps the low-side switch in the on state at the time of stop. Perform specific control. By performing this specific control at the time of stop, the energization from the battery 15 to the motor 20 is stopped, and the recirculation current flows due to the magnetic energy stored in the motor 20.

Therefore, when the stop condition is satisfied, the energization of the motor 20 can be stopped while suppressing the regenerative current from the motor 20 to the battery 15.
Further, the specific execution time for performing the specific control at the time of stop is set to be longer than the time required for the recirculation current to become zero. Therefore, all the magnetic energy stored in the motor 20 when the stop condition is satisfied can be consumed by the recirculation current, so that the regenerative current from the motor 20 to the battery 15 can be suppressed more effectively.

Further, as stop conditions, it is set that the trigger switch 10 is turned off, the value of the power supply current exceeds the first overcurrent threshold value, and a specific behavior occurs, and these 3 are set during normal drive control. If any one of the stop conditions is satisfied, the control is switched to the stop specific control.

Therefore, even when an abnormal state occurs in which the value of the power supply current exceeds the first overcurrent threshold value, the battery 15 to the motor 20 is energized while suppressing the generation of the regenerative current from the motor 20 to the battery 15. Can be stopped. Further, even when the trigger switch 10 is turned off by the user, the rotation of the motor 20 can be stopped while suppressing the regenerative current from the motor 20 to the battery 15.

Further, if the value of the power supply current still exceeds the second overcurrent threshold value even after the shift to the specific control at the time of stop, all the switching elements Q1 to Q6 of the drive circuit 21 can be turned off.

(1-6) Correspondence with the wording of the claims Here, the correspondence between the wording of the first embodiment and the wording of the claims will be described. The battery 15 corresponds to an example of a DC power supply. Each diode D1 to D6 corresponds to an example of a rectifying element. Of the six switching elements Q1 to Q6, the three switching elements Q1 to Q3 as high-side switches correspond to an example of positive electrode side switching elements, and the three switching elements Q4 to Q6 as low-side switches are examples of negative electrode side switching elements. Corresponds to. The trigger switch 10 corresponds to an example of an operation unit. The rotation position detection unit 23 and the current detection unit 24 correspond to an example of the drive state detection unit.

[2. Second Embodiment]
Since the basic configuration of the second embodiment is the same as that of the first embodiment, the differences will be described below. The same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

In the second embodiment, the switching element that is turned off in the specific control when stopped and the switching element that holds the on state are different from those in the first embodiment. That is, in the first embodiment, when the stop condition is satisfied and the stop specific control is started, the high side switch of the two switching elements turned on at that time is turned off, and the low side switch is turned on. Hold it. On the other hand, in the second embodiment, contrary to the first embodiment, the low side switch is turned off and the high side switch is kept in the on state.

For example, it is assumed that the U-phase high-side switch Q1 and the W-phase low-side switch Q6 are turned on, so that a current is flowing along the path indicated by the broken line arrow in FIG. In this state, when the stop condition is satisfied and the control is switched to the specific control at the time of stop, the U-phase high-side switch Q1 is held in the on state and the W-phase low-side switch Q6 is turned off.

As a result, a circulating current flows between the motor 20 and the drive circuit 21 along the path shown by the alternate long and short dash arrow in FIG. That is, a recirculation current flows from the third terminal 20c of the motor 20 through the diode D3 of the W-phase high-side switch Q3 and the U-phase high-side switch Q1 to the first terminal 20a of the motor 20. Therefore, in the second embodiment as well, the same effects as those in the first embodiment can be obtained.

[3. Third Embodiment]
Since the basic configuration of the third embodiment is the same as that of the first embodiment, the differences will be described below. The same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

In the first embodiment described above, the high-side switch of the two turned-on switching elements is turned off when switching to the specific control at the time of stop. Further, in the second embodiment described above, when switching to the specific control at the time of stopping, the low side switch of the two on switching elements was turned off, contrary to the first embodiment.

On the other hand, in the third embodiment, when switching to the specific control at the time of stop, that is, when the stop condition is satisfied, the switching element driven by PWM is turned off, and the switching element is not driven by PWM and is fixed to the on state. The switching element is kept on as it is.

For example, as illustrated in FIG. 9, it is assumed that the stop condition is satisfied at time t2 with the U-phase high-side switch Q1 and the W-phase low-side switch Q6 turned on. Further, when the stop condition was satisfied at time t2, of the two switching elements Q1 and Q6 to be turned on, the U-phase high-side switch Q1 was fixed in the on state, and the W-phase low-side switch Q6 was PWM-driven. It shall be.

In this case, when the control is switched to the stop specific control at time t2, the U-phase high-side switch Q1 fixed to the on-state is kept on as it is, and the PWM-driven W-phase low-side switch Q6 is turned off. In FIG. 9, the operation example before the time t2 is exactly the same as the operation example before the time t2 in FIGS. 4 and 6.

Therefore, even in the third embodiment, the same action and effect as in the first embodiment can be obtained. Moreover, in the third embodiment, when the stop condition is satisfied, the PWM-driven switching element is turned off, and the switching element fixed in the on state is kept in the on state as it is. Therefore, it is possible to reduce the processing load required for switching from the normal drive control to the stop specific control when the stop condition is satisfied.

[4. Fourth Embodiment]
In the first to third embodiments, the motor 20 is a brushless motor, and the drive circuit 21 is an inverter having six switching elements Q1 to Q6. On the other hand, in the fourth embodiment, configuration examples different from those of the first to third embodiments are shown as the motor and the drive circuit.

The electric working machine 40 of the fourth embodiment is shown in FIG. The electric work machine 40 shown in FIG. 10 is different from the electric work machine 1 of the first embodiment shown in FIG. 2 mainly in the following three points. The first is that the motor 50 is a brushed DC motor. The second is that the drive circuit 41 is an H-bridge circuit. Third, the rotation position detection unit 23 is not mounted.

The motor 50 as a brushed DC motor has two terminals 50a and 50b into which battery power is input. These terminals 50a and 50b are connected to windings (not shown) inside the motor 50.

The drive circuit 41 is configured as a so-called H-bridge circuit having four switching elements Q11, Q12, Q13, and Q14. In the drive circuit 41, the two switching elements Q11 and Q12 as high-side switches are connected to the positive electrode side energization paths, which are the energization paths connecting the terminals 50a and 50b of the motor 50 and the positive electrode side of the battery 15, respectively. It is provided. Further, the two switching elements Q13 and Q14 as low-side switches are provided in each negative electrode side energization path which is each energization path connecting the terminals 50a and 50b of the motor 50 and the negative electrode side of the battery 15. ..

Further, each switching element Q11 to Q14 is an n-channel MOSFET in this embodiment. Therefore, diodes (so-called parasitic diodes) D11 to D14 in the forward direction from the source to the drain are connected in parallel between the drain and the source of the switching elements Q11 to Q14, respectively. The diodes D11 to D14 are connected so as to allow energization from the negative electrode side to the positive electrode side of the battery 15.

In the electric work machine 40 configured as described above, the control unit 42 executes normal drive control when the trigger switch 10 is turned on. Specifically, any one of the two switching elements Q11 and Q12 as the high-side switch and any one of the two switching elements Q13 and Q14 as the low-side switch are turned on. Also in this embodiment, one of the two switching elements to be turned on may be fixed on and the other may be PWM-driven.

In normal drive control, for example, as shown in FIGS. 11 and 12, it is assumed that the switching element Q11 on the high side side and the switching element Q14 on the low side side are turned on. In this case, a current flows from the battery 15 to the motor 50 along the path shown by the broken line arrow in FIG. That is, a current flows from the positive electrode of the battery 15 through the switching element Q1 on the high side, the motor 50, the switching element Q4 on the low side, and the current detection unit 24 to the negative electrode of the battery 15. When the switching element to be turned on is switched to the other two switching elements Q2 and Q3, the rotation direction of the motor 50 is switched.

In FIG. 12, the period before the time t2 is the period during which the normal drive control is executed, and the time t2 is the timing at which the normal drive control is switched to the stop time specific control when the stop condition is satisfied.

As shown in FIG. 12, it is assumed that an abnormal state in which the motor 50 locks occurs at time t1. When the motor 50 locks at time t1 and the rotation speed decelerates or stops, the values of the motor current and the power supply current increase as compared with those during normal driving.

Then, when the value of the power supply current exceeds the first overcurrent threshold value at time t2, if both the two switching elements Q11 and Q14 that are turned off are turned off, the magnetic energy stored in the motor 50 causes. , Regenerative current to the battery 15 is generated.

The regenerative current in this case is generated as shown by the waveforms of the power supply current and the motor current shown between the time t2 and the time t3 in FIG. 12, and in the path indicated by the single-point chain arrow in FIG. Then, as shown in FIG. 12, the power supply voltage temporarily rises due to this regenerative current.

Therefore, similarly to the first to third embodiments, the control unit 42 of the present embodiment also executes the stop-time specific control for a predetermined period when the stop condition is satisfied during the normal drive control. An example of the stop-time specific control of the present embodiment will be specifically described with reference to FIGS. 13 and 14. In the present embodiment, when the stop condition is satisfied during the normal drive control, the switching element on the high side side of the two turned on switching elements is turned off as the stop specific control as in the first embodiment. Therefore, the switching element on the low side is kept in the ON state. In FIG. 13, the current path during normal drive control indicated by the broken line arrow is the same as that in FIG. Further, in FIG. 14, the operation example before the time t2 is exactly the same as the operation example before the time t2 in FIG.

As shown in FIG. 14, when the motor 50 is locked at time t1 and the value of the power supply current rises, and when the value of the power supply current exceeds the first overcurrent threshold value at time t2, the motor 50 is stopped for a predetermined period. Specific control is performed. Similar to the first embodiment, the predetermined period of the present embodiment is also a period from the timing when the value of the power supply current exceeds the first overcurrent threshold value to the elapse of the specific execution time. It is a period up to t5.

In the example of FIG. 14, at the time t2 when the value of the power supply current exceeds the first overcurrent threshold value, the switching element Q11 on the high side side and the switching element Q14 on the low side side are turned on. That is, the current is flowing along the path indicated by the broken line arrow in FIG. When the stop specific control is executed in this state, as shown in FIG. 14, the switching element Q11 on the high side side is turned off, and the switching element Q14 on the low side side is held in the on state.

As a result, a circulating current flows between the motor 50 and the drive circuit 41 along the path shown by the alternate long and short dash arrow in FIG. That is, a recirculation current flows from the second terminal 50b of the motor 50 through the switching element Q14 on the low side and the diode D13 of the switching element Q13 on the low side to the first terminal 50a of the motor 50.

Therefore, when the stop specific control is started at time t2, as shown in FIG. 14, the power supply current detected by the current detection unit 24 becomes 0, and a recirculation current flows between the motor 50 and the drive circuit 41. .. The recirculation current gradually decreases and becomes 0 at time t4. Then, at time t5, the stop specific control ends. After the end of the stop specific control, in the present embodiment, all the switching elements Q11 to Q14 of the drive circuit 41 are turned off.

Further, also in the electric work machine 40 of the present embodiment, the control unit 42 executes the energization stop process shown in FIG. 7 after the start of the normal drive control.
Therefore, also in the electric work machine 40 of the present embodiment, when the stop condition is satisfied during the normal drive control, the same effect as that of the first embodiment can be obtained.

[5. Other embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and can be implemented in various modifications.

(5-1) As a method for setting the specific execution time for executing the specific control at the time of stop, the method described in the first embodiment, that is, the time required for the recirculation current to become zero is theoretically or experimentally obtained. The method of setting a value obtained by adding a certain margin to the obtained time as the specific execution time is only an example. The specific execution time for executing the specific control at the time of stop may be set by various other methods.

Further, it is not essential to perform the stop specific control until the recirculation current becomes 0, and the stop specific control may be terminated while the recirculation current is still flowing. Even in that case, the specific execution time for executing the specific control at the time of stop may be appropriately determined. For example, the time during which the magnetic energy of the motor can be consumed to the extent that the rise in the power supply voltage can be suppressed to a certain level or less even if the regenerative current is generated is theoretically or experimentally obtained, and the time or more has passed. Up to a specific timing may be set as a specific execution time.

Further, it is not essential to set a period from the establishment of the stop condition to the elapse of a certain time such as the above-mentioned specific execution time as a predetermined period for executing the specific control at the time of stop. For example, the period from the establishment of the stop condition to the establishment of the specific end condition for terminating the specific control at the time of stop may be set as a predetermined period.

Specifically, for example, when the value of the recirculation current is actually detected, the period until the detected value becomes 0, or the period until a certain period of time elapses after the detected value becomes 0 is stopped. It may be set as a predetermined period for executing the specific control. In that case, it may be appropriately determined where to specifically provide the detection unit for detecting the value of the recirculation current in the path of the recirculation current.

Further, for example, when a stop condition other than that the trigger switch 10 is turned off is satisfied, the stop specific control is executed for the period from when the stop condition is satisfied until the trigger switch 10 is turned off. It may be set in a predetermined period.

Further, for example, the rotation speed of the motor 20 is monitored based on the signal input from the rotation position detection unit 23, and after the stop condition is satisfied, the rotation speed of the motor 20 is a value that is a certain amount lower than the rotation speed when the stop condition is satisfied. The period until becomes may be set to a predetermined period for executing the specific control at the time of stop. Regardless of the rotation speed when the stop condition is satisfied, the period until the rotation speed of the motor 20 becomes equal to or less than a predetermined constant rotation speed after the stop condition is satisfied is a predetermined period for executing the stop specific control. May be set to.

Further, for example, it is not essential to set the time when the stop condition is satisfied as the start of the specific control at the time of stop (that is, the start of the predetermined period), and wait until the predetermined start condition is satisfied after the stop condition is satisfied and start. When the condition is satisfied, the specific control at the time of stop may be started (that is, the start of a predetermined period). In this case, the starting conditions may be appropriately determined. As the start condition, for example, it may be set that a certain time elapses after the stop condition is satisfied.

That is, the predetermined period for executing the stop time specific control may be set by various methods at the start, end, and time.
(5-2) As the stop conditions that are the conditions for switching from the normal drive control to the specific control at the time of stop, the trigger switch 10 is turned off, the value of the power supply current exceeds the first overcurrent threshold, and the specific behavior. Is just an example. Only one of these three may be set as the stop condition, or any two may be set as the stop condition. Further, at least one or more stop conditions different from these three may be set.

For example, the stop condition may be set so that the rotation speed of the motor is equal to or less than the threshold value. It is conceivable that the motor locks as one of the factors that reduce the rotation speed of the motor. Therefore, a threshold value is set for the rotation speed of the motor, and when the rotation speed becomes equal to or less than the threshold value, the motor is stopped while suppressing the regenerative current to the battery 15 when the lock occurs by switching to the specific control at the time of stop. Can be done.

(5-3) It is only an example that the rectifying element connected in parallel to the switching element is a parasitic diode originally possessed by the switching element itself. A diode may be connected in parallel separately from the switching element itself.

(5-4) The configuration in which the battery pack 5 can be attached to and detached from the main body 3 is merely an example. For example, the battery 15 may be built in the main body 3. Further, for example, an input unit (for example, a DC jack) for inputting DC power from the outside of the electric work machine may be provided, and the DC power may be taken in from the input unit and supplied to the drive circuit.

Further, the DC power source for driving the motor, that is, the power source of the DC power input to the drive circuit is not limited to the battery 15, and may be another power source. For example, the configuration may be such that AC power is taken in from an external commercial power source or the like, the AC power is converted into DC power by an AC / DC converter or the like, and the converted DC power is input to the drive circuit. In the case of this example, a component that converts AC power into DC power, such as an AC / DC converter, corresponds to the DC power supply of the present disclosure.

(5-5) The above driver drill is merely an example as an electric work machine to which the present disclosure can be applied. The present disclosure is not limited to driver drills, and can be applied to various electric work machines such as electric tools for gardening, masonry, metalworking, and woodworking. More specifically, electric hammers, electric hammer drills, electric drills, electric drivers, electric wrench, electric grinders, electric reciprocating saws, electric jigsaws, electric hammers, electric cutters, electric chainsaws, electric circular saws, electric canna, electric nail cutters ( (Including tacking machines), electric hedge trimmers, electric lawnmowers, electric lawn mowers, electric brush cutters, electric cleaners, electric blowers, electric sprayers, electric sprayers, electric dust collectors, etc. Disclosure can be applied.

(5-6) A plurality of functions possessed by one component in the above embodiment may be realized by a plurality of components, or one function possessed by one component may be realized by a plurality of components. May be good. Further, a plurality of functions possessed by the plurality of components may be realized by one component, or one function realized by the plurality of components may be realized by one component. Further, a part of the configuration of the above embodiment may be omitted. In addition, at least a part of the configuration of the above embodiment may be added or replaced with the configuration of the other above embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

1,40 ... Electric work machine, 5 ... Battery pack, 10 ... Trigger switch, 12 ... Forward / reverse switch, 14 ... Mode selector switch, 15 ... Battery, 20,50 ... Motor, 20a, 50a ... First terminal, 20b, 50b ... 2nd terminal, 20c ... 3rd terminal, 21,41 ... Drive circuit, 22, 42 ... Control unit, 22a ... CPU, 22b ... Memory, 23 ... Rotation position detection unit, 24 ... Current detection unit, 26 ... Acceleration Sensor, 31, 32, 33 ... Winding, 120 ... Electric angle, D1 to D6, D11 to D14 ... Diode, Q1 to Q6, Q11 to Q14 ... Switching element.

Claims (5)

A motor that has multiple terminals for inputting power from a DC power supply,
Individually divided into a plurality of positive electrode side energization paths connecting each of the plurality of terminals and the positive electrode side of the DC power supply, and a plurality of negative electrode side energization paths connecting each of the plurality of terminals and the negative electrode side of the DC power supply. Has a plurality of switching elements that conduct and cut off each of the current-carrying paths, and is individually connected in parallel to each of the plurality of switching elements to allow power-carrying from the negative electrode side to the positive electrode side of the DC power supply. With a drive circuit having multiple rectifying elements configured to
A current detection unit configured to detect the value of the current supplied from the DC power supply to the drive circuit, and
A control unit configured to control the drive of the motor by individually controlling the on / off of the plurality of switching elements included in the drive circuit.
With
The control unit
Of the plurality of switching elements, any one of the positive electrode side switching elements provided in each of the plurality of positive electrode side energization paths, and among the plurality of switching elements, the plurality of negative electrode side energization paths. Normal drive control that rotates the motor by turning on any one of the negative electrode side switching elements provided in each, and
When the stop condition for stopping the power supply from the DC power supply to the motor is satisfied during the rotation of the motor by the normal drive control, one of the two switching elements turned on for a predetermined period of time. Turn off and keep the other on, specific control when stopped,
Is configured to run
The control unit is configured to turn off the switching element held in the ON state when the value of the current detected by the current detection unit is equal to or greater than the threshold value after the start of the stop specific control. There is an electric work machine. The electric work machine according to claim 1.
The predetermined period is set as a period from the start of the specific control at the time of stop to a predetermined timing in which the time required for the recirculation current flowing by the magnetic energy stored in the motor to become zero has elapsed.
The recirculation current is a current that flows between the motor and the drive circuit without going through the DC power supply, and is connected to the terminal of the motor to which the one switching element turned off is connected. A current flowing through the rectifying element connected in parallel to the other switching element, the motor, and the other switching element held in the on state.
Electric work machine. The electric work machine according to claim 1 or 2.
The control unit
As the normal drive control, among the positive electrode side switching element and the negative electrode side switching element to be turned on, one switching element is fixed in the on state and the other switching element is PWM-driven.
In the stop specific control, when the stop condition is satisfied, the switching element that has been PWM-driven is turned off, and the switching element that has been fixed in the on state is held in the on state.
Electric work machine. The electric work machine according to any one of claims 1 to 3.
A drive state detection unit for detecting the drive state of the motor is provided.
The control unit is configured to perform an abnormality determination process for determining whether or not the drive state of the motor is an abnormal state based on the detection result by the drive state detection unit.
The stop condition is that the driving state of the motor is determined to be the abnormal state by the abnormality determination process.
Electric work machine. The electric work machine according to any one of claims 1 to 4.
It is provided with an operation unit operated to instruct the rotation or stop of the motor.
The stop condition is that an operation for stopping the rotation of the motor is performed on the operation unit.
Electric work machine.

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